mongodb slow query with $near and other condition - mongodb

Question

I have a mongodb collection named rooms, and it has a 2d index for field location. I've queried like this:
db.rooms.find( { "location" : { "$near" : { "latitude" : 37.3356135, "longitude" : 127.12383030000001 } }, "status": "open", "updated" : { "$gt" : ISODate("2014-06-03T15:34:22.213Z") }}).explain()
The result:
{
"cursor" : "GeoSearchCursor",
"isMultiKey" : false,
"n" : 7,
"nscannedObjects" : 143247,
"nscanned" : 143247,
"nscannedObjectsAllPlans" : 143247,
"nscannedAllPlans" : 143247,
"scanAndOrder" : false,
"indexOnly" : false,
"nYields" : 0,
"nChunkSkips" : 0,
"millis" : 1457,
"indexBounds" : {
},
"server" : "ip-10-162-39-56:27017",
"filterSet" : false
}
Sometimes it takes more than 2000ms. But if I remove the $gt condition for updated field, the query is fast, about 5~30ms.
> db.rooms.find( { "location" : { "$near" : { "latitude" : 37.3356135, "longitude" : 127.12383030000001 } }, "status": "open"}).explain()
{
"cursor" : "GeoSearchCursor",
"isMultiKey" : false,
"n" : 100,
"nscannedObjects" : 1635,
"nscanned" : 2400,
"nscannedObjectsAllPlans" : 1635,
"nscannedAllPlans" : 2400,
"scanAndOrder" : false,
"indexOnly" : false,
"nYields" : 0,
"nChunkSkips" : 0,
"millis" : 22,
"indexBounds" : {
},
"server" : "ip-10-162-39-56:27017",
"filterSet" : false
}
I've tried compound index for {location:"2d", updated: -1} but it didn't work. How can I make this query faster?